The present invention applies to the domain of electron-beam lithography. To allow the etching of patterns whose critical dimension is below 50 nm, it is necessary to integrate into the methods of optical photolithography schemes for correcting the optical distortions that are increasingly complex both at the mask design and production stage and at the exposure stage. The costs of the equipment and developments for a new generation of technology consequently increase in very high proportions. Today, the critical dimensions accessible in photolithography are greater than or equal to 65 nm. The 32-45 nm generation is undergoing development and there is no viable solution envisaged for technological nodes below 22 nm. For its part, electron-beam lithography already allows the etching of 22-nm patterns; it does not require any mask and offers a fairly short development time, thus allowing better reactivity and flexibility in the realization of improvements to the technologies and to the designs. On the other hand, the production times are structurally substantially higher than in photolithography since it is necessary to carry out step-wise exposure (with a “stepper”), whereas photolithography requires only layer-wise exposure.
The electron beam or beams used to perform the etching of a pattern scatter notably over short distance (forward scattering or blur) in the resin and the substrate on the edges of the center of the beam, thus increasing the size of the beam and reducing its contrast. Moreover, the electrons are completely backscattered over a long distance (backward scattering). In particular, the line ends within dense networks will be shortened (“line end shortening” or LES), thus affecting the functionality of the component and therefore decreasing production efficiency.
A certain number of prior art methods, in the domains of photolithography and electron-beam lithography, have attempted to afford corrections to this LES phenomenon. Such is notably the case in photolithography of the methods providing for the modifications of the patterns to be etched, notably by extending their surface at the line end, such as those disclosed by K. Tsudaka et al., Japanese Journal of Applied Physics, Vol. 36 (1997), pp. 7477-7481, K. Kim et al., Japanese Journal of Applied Physics, Vol. 37 (1998), pp. 6681-6685 as well as by U.S. Pat. No. 7,494,751.
Similar methods have been applied in electron-beam lithography, such as those disclosed notably by S. Manakli et al., Japanese Journal of Applied Physics, Vol. 45, No. 8A, 2006, pp. 6462-6467, in which the dimensions of the lines are modified as a function of rules, and the international patent application published under the number WO2007/129135, in which a line is replaced with several lines of chosen widths and spacings. However, a solution remains to be found allowing the correction of LESs while affording sufficient resolution for technological nodes of less than or equal to 22 nm.